@electron/packer 18.3.6 uses extract-zip 2.0.1, which hangs forever when run by recent node versions: Zip extraction fail in Node 26.1.0 · Issue #154 · max-mapper/extract-zip · GitHub, https://github.com/electron/electron/issues/51619.
I think the simplest solution is to switch to version 20.0.1 of @electron/packager, where they replaced the dependency with their own, maintained version: fix: swap `extract-zip` with `@electron-internal/extract-zip` by erickzhao · Pull Request #1917 · electron/packager · GitHub.